An attacker with access to JSON services can cause Java code written in the the title or the description of a calendar to execute. If the attacker also has permission to create events in the Calendar portlet, the attacker will be able to execute any Java code on the server.

Workaround

Disable JSON service's access to CalEventServiceUtil by adding "com.liferay.portlet.calendar.service.CalEventServiceUtil" to the "json.service.invalid.class.names" property in portal-ext.properties. For example: